Complex systems like databases, compilers, and browsers are often seen as black boxes by users, but they are essentially just code. By focusing on the core ideas and minimizing unnecessary details, you can recreate seemingly complex software. For example, building a compiler can help you understand concepts like parsing with recursion and representing a program as a tree. Similarly, building a database from scratch can teach you about power-loss atomicity, indexing with data structures like B+trees, and implementing a SQL-like query language. This approach breaks down these complex systems into manageable parts, making them more accessible for programmers.
https://build-your-own.org/blog/20251015_db_in_3000/